Conventionally, epoxy resins are widely used in the electronic material fields as an epoxy resin composition that combines an epoxy resin and a curing agent. Among the electronic material fields, for example, in the applications such as a high refractive-index layer of an antireflective film (an antireflective film for a liquid crystal display, and the like), an optical thin film (such as a reflecting plate), a sealant for electronic parts, a printed wiring substrate, and an interlayer insulation film material (such as an interlayer insulation film material for a built-up printed substrate), performances such as high adhesion to a base material, hard coating property, heat resistance, and high transparency for visible light are required for a molding material.
Crystalline epoxy resins generally have a rigid backbone skeleton and are multifunctional, so the crystalline epoxy resins have high heat resistance and are used in a field in which reliability for heat resistance is required such as the electric/electronic field.
In some fields, however, there is an application in which nothing but a liquid composition can be molded such as in casting molding. Thus, crystalline epoxy resins are limited to be used only in an application in which a solid material is used such as in transfer molding, and therefore, a range in which the crystalline epoxy resins can be used is limited.
Conventionally, epoxy resins used for liquid molding such as casting molding are liquid epoxy resins and cannot satisfactorily satisfy demand for enhancing properties of cured products such as heat resistance for which requirements have become increasingly severe recently in fields such as adhering, casting, sealing, molding, and laminating. Thus, demand for liquefying crystalline multifunctional epoxy resins providing a cured product having high heat resistance has increased. There is also demand for thermally curing the liquid epoxy resins.
An epoxy resin produced by esterifying a part of epoxy groups of a highly crystalline epoxy compound, for example, tris-(2,3-epoxypropyl)-isocyanurate, to lower the crystallinity so as to liquefy the highly crystalline epoxy compound has been disclosed (see Patent Document 1).
A compound in which an epoxy ring is bonded to a triazinetrione ring through a long chain alkylene group has been disclosed (see Patent Document 2).
An epoxy compound in which an epoxy ring is bonded to a triazinetrione ring through a long chain alkylene group and an epoxy resin composition using the epoxy compound have been disclosed (see Patent Documents 3, 4, and 5).
An epoxy compound in which an epoxy cyclohexyl group is bonded to a triazinetrione ring through an oxyalkylene group and an epoxy resin composition using the epoxy compound have been disclosed (see Patent Document 6).
An epoxy compound having a cyanuric acid skeleton that is produced by reacting cyanuric chloride and an epoxy alcohol, and a curable compound using the epoxy compound have been disclosed (see Patent Document 7).